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Metal Oxide with High Thermal Stability and Preparing Method Thereof

a technology of metal oxide and thermal stability, which is applied in the direction of catalyst activation/preparation, metal/metal-oxide/metal-hydroxide catalyst, etc., can solve the problems of reducing specific surface area, and inevitably exposed to high temperatures of three-way catalysts for the purification of exhaust gas of vehicles. , to achieve the effect of high specific surface area, high crystallinity and superior thermal stability

Inactive Publication Date: 2008-10-02
HANWHA CHEMICAL CORPORATION
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention relates to a method for preparing metal oxide with high thermal stability and oxygen storage capacity, which can be used as an oxygen storage material or a support for a three way catalyst for the purification of exhaust gas from vehicles. The metal oxide has a specific surface area that is not drastically decreased and can maintain its oxygen storage capacity even at high temperatures. The method involves mixing cerium oxide with alumina and calcining it at high temperatures. The resulting metal oxide has improved thermal stability and oxygen storage capacity compared to conventional materials.

Problems solved by technology

Although the three way catalyst causes carbon monoxide (CO), hydrocarbons, or nitrogen oxide (NOx) to be highly converted in a very narrow range of air-to-fuel ratio of about 14.6, it is disadvantageous in that the conversion is drastically decreased in a range falling outside of the above air-to-fuel ratio.
However, the three way catalyst for the purification of exhaust gas of vehicles is inevitably exposed to high temperatures.
In such a case, cerium oxide suffers because it has a drastically decreased specific surface area and a greatly increased crystal size, attributable to the fusion of pores or sintering of crystals, and furthermore, oxygen storage capacity and oxygen mobility are lowered, that is, thermal stability is decreased.
However, this method is disadvantageous because the used alkali hydroxide is difficult to completely remove.
As such, [Ce0.8Zr0.2O2]*[0.4Al2O3] prepared in Example E7 has a specific surface area of 129 m2 / g, but has a specific area of 82 m2 / g after calcination at 650° C. for 4 hours, and therefore the thermal stability thereof is considered insufficient.

Method used

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  • Metal Oxide with High Thermal Stability and Preparing Method Thereof
  • Metal Oxide with High Thermal Stability and Preparing Method Thereof
  • Metal Oxide with High Thermal Stability and Preparing Method Thereof

Examples

Experimental program
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example 1

[0037]An aqueous mixture solution, comprising 5.81 wt % of zirconyl nitrate [30 wt % aqueous solution as ZrO2], 6.17 wt % of cerium nitrate [Ce(NO3)3.6H2O], and 9.02 wt % of aluminum nitrate [Al(NO3)3.9H2O], was pumped at a rate of 8 g per min through a tube having an outer diameter of ¼ inch and pressurized at 250 bar. 16.34 wt % of ammonia water [28 wt % NH3] was pumped at a rate of 8 g per min through a tube having an outer diameter of ¼ inch and pressurized at 250 bar. The pressurized aqueous mixture solution, comprising zirconyl nitrate, cerium nitrate, and aluminum nitrate, and the pressurized ammonia water were pumped into a tube-shaped continuous line mixer to thus be instantly mixed, and then allowed to precipitate for a residence time of about 30 sec. Further, deionized water was pumped at a rate of 96 g per min through a tube having an outer diameter of ¼ inch, preheated to 550° C., and pressurized at 250 bar. Subsequently, the deionized water thus preheated and the preci...

example 2

[0038]An aqueous mixture solution, comprising 2.43 wt % of zirconyl nitrate, 2.58 wt % of cerium nitrate, 0.37 wt % of lanthanum nitrate [La(NO3)3.6H2O], and 15.62 wt % of aluminum nitrate, was pumped at a rate of 8 g per min through a tube having an outer diameter of ¼ inch, and pressurized at 250 bar. 16.88 wt % of ammonia water was pumped at a rate of 8 g per min through a tube having an outer diameter of ¼ inch and pressurized at 250 bar. The pressurized aqueous mixture solution, comprising zirconyl nitrate, cerium nitrate, lanthanum nitrate, and aluminum nitrate, and the pressurized ammonia water were pumped into a tube-shaped continuous line mixer to thus be instantly mixed, and then allowed to precipitate for a residence time of about 30 sec. Further, deionized water was pumped at a rate of 96 g per min through a tube having an outer diameter of ¼ inch, preheated to 550° C., and pressurized at 250 bar. Subsequently, the preheated deionized water and the precipitate resulting ...

example 3

[0039]An aqueous mixture solution, comprising 2.10 wt % of zirconyl nitrate, 0.56 wt % of cerium nitrate, and 18.34 wt % of aluminum nitrate, was pumped at a rate of 8 g per min through a tube having an outer diameter of ¼ inch, and was pressurized at 250 bar. 17.17 wt % of ammonia water was pumped at a rate of 8 g per min through a tube having an outer diameter of ¼ inch and pressurized at 250 bar. The pressurized aqueous mixture solution, comprising zirconyl nitrate, cerium nitrate, and aluminum nitrate, and the pressurized ammonia water were pumped into a tube-shaped continuous line mixer to thus be instantly mixed, and were then allowed to precipitate for a residence time of about 30 sec. Further, deionized water was pumped at a rate of 96 g per min through a tube having an outer diameter of ¼ inch, preheated to 550° C., and pressurized at 250 bar. Subsequently, the preheated deionized water and the precipitate resulting from the line mixer, which were in a state of being pressu...

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Abstract

Disclosed are metal oxide having high thermal stability and a preparation method thereof, specifically including continuously reacting a reaction mixture, composed of (i) water, (ii) a first metal salt including an aqueous cerium compound and (iii) a second metal salt including an aqueous aluminum compound, at 200˜700° C. under pressure of 180-550 bar, the reaction product having a molar ratio of metal, other than aluminum, to aluminum of 0.1˜10.

Description

TECHNICAL FIELD[0001]The present invention relates to metal oxide having high thermal stability and a method of preparing the same, in which the specific surface area of metal oxide is maintained very high even after high-temperature calcinations, compared to conventional materials for storing oxygen, advantageously leading to oxygen storage oxide nanoparticles having high thermal stability.[0002]The metal oxide prepared by the method of the present invention may be used as oxygen storage capacity (OSC) material or a support for a three way catalyst for the purification of exhaust gas from gasoline vehicles, and may also be used for the purification of exhaust gas of diesel vehicles, chemical reaction, or in an oxygen sensor for detecting oxygen therein. Preferably, the metal oxide is predicted to be suitable for use as such OSC material or support for a three way catalyst for the purification of exhaust gas of gasoline vehicles.BACKGROUND ART[0003]Generally, a three way catalyst fu...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): B01J23/10C01G99/00
CPCB01J23/002B01J23/10B01J37/031B01J2523/00B82Y30/00C01B13/363C01B13/366C01G25/00C01P2004/03C01P2004/20C01P2004/32C01P2004/50C01P2004/64C01P2006/12C01P2006/13B01J2523/31B01J2523/3712B01J2523/48C01G99/00C01F7/00
Inventor MYEONG, WAN JAELEE, JOO HYEONGSONG, KYU HO
Owner HANWHA CHEMICAL CORPORATION
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